> ## Documentation Index
> Fetch the complete documentation index at: https://docs.layerzero.network/llms.txt
> Use this file to discover all available pages before exploring further.

# Deployed Endpoints, Message Libraries, and Executors

> Learn about Deployed Endpoints, Message Libraries, and Executors in LayerZero V2. Understand the architecture, core concepts, and how it enables omnichain in...

Below you can find a description of the main LayerZero V2 contracts and find the corresponding deployment information for each blockchain network LayerZero supports.

> [!NOTE]
>
> **Endpoint Id** (`eid`) values have no relation to **Chain Id** (`chainId`) values. Since LayerZero spans both EVM and non-EVM chains, each Endpoint contract has a unique identifier known as the `eid` for determining which chain's `endpoint` to send to or receive messages from.
>
> When using LayerZero contract methods, be sure to use the correct `eid` listed below:
>
> * `30xxx`: refer to mainnet chains
>
> * `40xxx`: refer to testnet chains
>
> To see if a specific LayerZero contract supports another, use the `isSupportedEid()` method.

## Contract Description

| **Contract Name** | **Description** |
| - | - |
| **EndpointV2** | The primary entrypoint into LayerZero V2 responsible for managing crosschain communications. It orchestrates message sending, receiving, and configuration management between various smart contract connections using message library contracts and internal mappings to track `OApp` specific settings. |
| **SendUln302** | A message library for sending crosschain messages. It combines functionalities from `SendUlnBase` and `SendLibBaseE2` to ensure secure message dispatch. |
| **ReceiveUln302** | A message library for receiving and verifying crosschain messages. It integrates `ReceiveUlnBase` and `ReceiveLibBaseE2` to maintain message integrity. |
| **SendUln301** | A version of the send message library compatible with `EndpointV1` for backwards compatibility with `EndpointV2`. |
| **ReceiveUln301** | A version of the receive message library compatible with `EndpointV1` for backwards compatibility with `EndpointV2`. |
| **LZ Executor** | A contract responsible for executing received crosschain messages automatically with a specified `gas limit` and `msg.value` for a fee. |
| **LZ Dead DVN** | Represents a **[Dead Decentralized Verifier Network (DVN)](https://docs.layerzero.network/v2/concepts/glossary.md#dead-dvn)**. These contracts are placeholders used when the default LayerZero config is inactive and will require the OApp owner to manually configure the contract's config to use the pathway. |
| **Blocked Message Library** | A message library that blocks messages from being sent or received. Used to disable specific pathways at the protocol level. |

## Checking Default Configs

To see the default configuration for a given pathway (i.e., from `Chain A` to `Chain B`), you can use [LayerZero Scan's Default Checker](https://layerzeroscan.com/tools/defaults?version=V2).

![LayerZero Scan Default Configurations interface showing a table of pathway configurations from Ethereum to various destinations, displaying columns for Send Library (SendUln302), Receive Library (ReceiveUln302), DVN providers (LayerZero Labs, Google), Executor, and confirmation requirements](https://mintcdn.com/layerzero/qVdya_xVZRutFzkr/images/defaultchecker.png?fit=max\&auto=format\&n=qVdya_xVZRutFzkr\&q=85\&s=5f2c64f8eacbff0796557ffb68056b57)